1. Technical Field
The present disclosure relates to a ternary content addressable memory device and a method thereof, more particularly to a ternary content addressable memory device for software defined networking, which separates a forwarding rule into two parts and uses different types of ternary content addressable memories for filtering and searching, and a method thereof.
2. Description of Related Arts
In recent years, network is rapidly developed and popularized, and network traffic and amount of information are also growing fast. For this reason, many companies pay attention on how to effectively manage the ever-increasing network. Among network management technologies, software defined networking technology attracts the most attention.
Simply put, in conventional network, local routers or local switches manage their packet forwarding rules respectively, but in the software defined networking technology, the packet forwarding rules are in centralized management, and the network can be changed and re-planed by using program in a centralized management manner without changing hardware devices, in order to quickly search the best path for forwarding packet. In the actual implementation, the software defined networking is based on OpenFlow protocol which has characteristics of allowing a longer, variable words length, don't care bit and dispersion. However, it is hard to adapt these characteristics to conventional ternary content addressable memory with fixed words length.
In addition, the ternary content addressable memory consumes a lot of power, and the reason is that match lines of the ternary content addressable memory are charged in preparation for each search, and the match lines which are mismatched are then discharged, and most of the match lines discharge because the mismatched match lines are much more than the matched match lines, and it causes great power consumption. As a result, the conventional ternary content addressable memory has problems of poor flexibility in words length and large power consumption.
There are companies developing technical means to reduce power consumption of the match line, in order to reduce power consumption of the ternary content addressable memory. However, the ternary content addressable memory applying this technical means is still unable to change the words length of the search data, that is, the words length is short and invariable, and the problem of poor flexibility in words length still exists.
Therefore, what is need is to develop a ternary content addressable memory device to solve the problems of high power consumption and poor flexibility in words length.